Shooting And Trapping
Pesticides And Other Contaminants/Toxics
Recovery of American Redstart population in Maritime Provinces after 1966 suggests decreasing effect of prior DDT spraying (Erskine 1992a).
Collisions With Stationary Objects
Stationary objects such as TV towers kill hundreds of individuals at widely separated sites during nocturnal fall and spring migrations (Post and Gauthreaux 1989, Robbins 1991, Stevenson and Anderson 1994b). For example, 908 individuals were killed at a tower in Orange County, Florida, during 4 fall seasons, and 728 individuals at another tower (Stevenson and Anderson 1994b). This source of annual mortality probably affects total population little, but its magnitude is difficult to estimate accurately. No information on power lines or antennae.
Degradation Of Habitat
For effects of brood parasitic Brown-headed Cowbird and nest predators associated with fragmented forest landscapes and human residential activities, see Demography and Populations: Population Regulation. Additional factors that continue to degrade redstart habitat, at least locally, include particular silvicultural practices, streamside use by humans in the western U.S., herbicide reversion of suitable habitat to spruce–fir in parts of Maine, conversion of deciduous habitats to pine monoculture in Alabama and Mississippi (reviewed by Sallabanks 1993e), and forest maturation.
During overwintering periods, preference for relatively undisturbed (forested) habitats over most human-modified ones indicates that human occupancy of Caribbean islands, and probably other parts of the overwintering range, has likely decreased global population of this species during twentieth century (Sherry and Holmes 1996a; A. Sliwa, TWS, and RTH, unpublished data). Can reach moderate overwintering densities in such habitats as citrus orchards, shade coffee plantations, grazed savannas, and residential areas with trees (Sherry and Holmes 1996a); thus, not all human activities threaten the species. Work is currently under way to identify how specific human-modified habitats influence overwinter abundance and survival of redstarts and of other migrant birds in Caribbean region (TWS, RTH). Drought-deciduousness (i.e., facultative dropping of leaves under condition of scarce soil water) in Caribbean dry forests decreases overwinter persistence of American Redstart (Sherry and Holmes 1996a), suggesting that human-caused climate change could be important to overwinter habitat suitability.
Disturbance At Nest And Roost Sites; Human/Research Impacts
Little specific information. Female will abandon nest site if disturbed during nest-building, but once eggs are laid, she tolerates human visits, nearby video recorders, handling of chicks, and capture with hoop-net at nest site (TWS, RTH).
Little research available on economic value of redstarts, except that they consume large quantities of insects throughout the year, and they opportunistically eat large numbers of the most economically important coffee pest, the coffee berry borer (Hypothenemus hampei; Sherry et al. 2016). The likelihood that redstarts contribute to helping control abundance of this insect pest is increased by experiments showing that small insectivorous birds generally limit its abundance enough to save coffee farmers in Jamaica an estimated $310.00/ha/y (Johnson et al. 2010d).